I think anti-virus should be part of the core os. This does kill all third party vendors - good riddance to most of them, sorry if there is one that isn't evil (I'm not aware of it)
Once the AV vendors exist, killing them, especially by Microsoft, is clearly anticompetitive.
If you could prevail on a government to decide that, maybe it could work.
One thing I see, is that AV has a component of maintaining a DB of signatures of bad things. This does not seem at all the job of the core os. Would the Debian team maintain such a DB?
It happens all the time that the big companies take something in house and kill a market. The car radio market is all but dead now that manufactures ship decent radios.
If you could prevail on a government to decide that, maybe it could work.
One thing I see, is that AV has a component of maintaining a DB of signatures of bad things. This does not seem at all the job of the core os. Would the Debian team maintain such a DB?